Directional drilling technology permits the drilling of a lateral or secondary borehole from a primary or mother borehole. Typically, lateral boreholes are drilled, and subsequently produced, through a gap or window cut or milled through a section of the existing casing string in the primary borehole. Alternately, the lateral borehole may extend from the downhole end of an existing casing string in the primary borehole. The lateral borehole thus extends from the primary borehole to a desired location in the formation.
The lateral borehole may be either cased or uncased. Where the lateral borehole is not fully cased, it may be desirable to hang or set a liner within the uncased portion of the lateral borehole to support the lateral borehole during production of the lateral borehole. In this case, the liner is preferably perforated to allow fluids to enter the lateral borehole for production to the surface.
Typically, an apparatus or mechanism is provided for hanging or otherwise positioning the liner within a casing string or other similar structure at or adjacent to the entrance to the lateral borehole, or within a portion of the lateral borehole itself, such that the liner extends within the lateral borehole. The apparatus also typically includes a packer or packer assembly for sealing the junction between the liner and the casing string.
Numerous packers or packing assemblies have been developed to provide the desired sealing effect within the borehole. Further, various mechanisms have been developed to install and actuate these packers in a desired position in the borehole. However, none have been found to be fully satisfactory.
For instance, the packer and attached liner are typically placed at a desired position within the borehole by a running tool connected with a working string extending from the surface. When in the desired position, the packer is set within the borehole and the running tool is removed to the surface with the working string.
However, the running tool with the packer may not be easily or readily insertable in the borehole due to the occurrence of a “piston” effect in the borehole during installation. To address the potential “piston” effect, the running tool and/or the packer may provide for a fluid bypass to permit fluids to pass through or past the running tool and/or the packer as they are being conducted downhole. However, it is often desirable to flush any drilling or other fluids from the lateral borehole following the installation of the liner and the packer and prior to the production of the lateral borehole. In this case, the presence of the fluid bypass may render any such desired flushing of the liner more difficult. As a result, a separate flushing tubing string is typically required to be subsequently inserted in the borehole to perform the flushing operation.
Thus, the absence of a fluid bypass may render the running tool and packer more difficult to conduct through the lateral borehole to the desired downhole position. However, the presence of the fluid bypass may render the subsequent flushing of the liner more difficult.
Further, the manner of actuating the packer and the releasing the running tool therefrom have not been found to be fully satisfactory. For instance, mechanically actuated or mechanically manipulated systems are typically used for setting the packer downhole and releasing the running tool. In other words, the working string is typically manipulated from the surface to actuate the packer and release the packer from the running tool mechanically downhole. For instance, a rotational force may be provided through rotation of the working string from the surface. As well, either tension or compression may be provided by moving the working string longitudinally in either an uphole or a downhole direction in the borehole. However, such mechanically actuated or mechanically manipulated systems may cause various difficulties.
For example, if the working string or any of the attached apparatus or liner becomes stuck within the borehole, it may not be possible to manipulate the working string in the desired manner to set the packer and/or release the running tool. Further, the packer is typically threadably connected with the running tool to be conducted downhole. Thus, manipulation of the working string, and particularly rotation of the working string, to set the packer may cause the packer to accidentally unthread from the running tool. Accordingly, such mechanically actuated systems may not always be desirable.
As well, the difficulties experienced with these mechanical systems may be intensified depending upon the orientation and depth of the borehole. Specifically, greater frictional resistance to the manipulation of the working string will tend to be encountered where the borehole is oriented more towards the horizontal and is of a significant length. In particular, the use of mechanical systems in long reach horizontal lateral boreholes has been found to be particularly challenging.
Examples of various forms of packers are provided by Canadian Patent Application No. 2,407,069 published Nov. 8, 2001 by Specialised Petroleum Services Group Limited, U.S. Pat. No. 4,345,649 issued Aug. 24, 1982 to Baugh et. al., U.S. Pat. No. 4,487,258 issued Dec. 11, 1984 to Jackson et. al., U.S. Pat. No. 4,526,229 issued Jul. 2, 1985 to Dickerson, U.S. Pat. No. 4,936,387 issued Jun. 26, 1990 to Rubbo, U.S. Pat. No. 5,810,082 issued Sep. 22, 1998 to Jordan, Jr., U.S. Pat. No. 5,826,661 issued Oct. 27, 1998 to Parker et. al., U.S. Pat. No. 6,119,783 issued Sep. 19, 2000 to Parker et. al. and U.S. Pat. No. 6,612,372 issued Sep. 2, 2003 to Freiheit et. al.
As a result, there remains a need in the industry for an improved system and an improved method for installing a liner conduit in a borehole. Further, there is a need for a hydraulically actuated system comprised of at least one of a packer assembly adapted for insertion in the borehole with a running tool and a running tool adapted for insertion in the borehole with a packer assembly. Finally, there is a need for a system and a method capable of installing a liner conduit in a long reach horizontal borehole.